Revise detail panel visibility rule

User studies proved the DM5 auto-closing detail panel is not optimal. It is too cumbersome to explicitly open it again after clearing the selection. These users actually like the persistent DM4 detail panel very much.

At the other hand the DM5 interface design regards an empty detail panel as it appears in DM4 (the "blue elephant") as a waste of valuable screen real estate which must be avoided.

Both positions can be satisfied at the same time by redesigning the existing detail panel toggle switch according to this rule:

ON -- The detail panel appears automatically as soon as there is a (single) topic/assoc selection. If there is no selection it goes away. Furthermore: details do not appear in-map (no animations!), unless pinned.

OFF -- The detail panel does not appear automatically. Instead the detail panel can be opened explicitly by context menu ("View", "Edit", "What's related?"). Details are displayed in-map.

So, the toggle acts not anymore as a vehicle to open/close the detail panel explicitly, but to state what type of user you are: